/*
 * #%L
 * Alfresco Repository
 * %%
 * Copyright (C) 2005 - 2023 Alfresco Software Limited
 * %%
 * This file is part of the Alfresco software. 
 * If the software was purchased under a paid Alfresco license, the terms of 
 * the paid license agreement will prevail.  Otherwise, the software is 
 * provided under the following open source license terms:
 * 
 * Alfresco is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * Alfresco is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with Alfresco. If not, see <http://www.gnu.org/licenses/>.
 * #L%
 */

package org.alfresco.filesys.alfresco;

import java.io.IOException;
import java.util.concurrent.Callable;
import jakarta.transaction.Status;
import jakarta.transaction.UserTransaction;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.alfresco.error.AlfrescoRuntimeException;
import org.alfresco.jlan.server.SrvSession;
import org.alfresco.jlan.server.filesys.TransactionalFilesystemInterface;
import org.alfresco.repo.transaction.RetryingTransactionHelper;

/**
 * Alfresco Tx Disk Driver Base Class
 * 
 * <p>
 * Provides common code to the Alfresco filesystem implementations.
 *
 * @author gkspencer
 */
public abstract class AlfrescoTxDiskDriver extends AlfrescoDiskDriver implements TransactionalFilesystemInterface
{
    private static final Log logger = LogFactory.getLog(AlfrescoTxDiskDriver.class);

    // Remember whether the current thread is already in a retrying transaction

    private ThreadLocal<Boolean> m_inRetryingTransaction = new ThreadLocal<Boolean>();

    /**
     * Begin a read-only transaction
     * 
     * @param sess
     *            SrvSession
     */
    public void beginReadTransaction(SrvSession sess)
    {
        beginTransaction(sess, true);
    }

    /**
     * Begin a writeable transaction
     * 
     * @param sess
     *            SrvSession
     */
    public void beginWriteTransaction(SrvSession sess)
    {
        beginTransaction(sess, false);
    }

    /**
     * Perform a retryable operation in a write transaction
     * <p>
     * WARNING : side effect - that the current transaction, if any, is ended.
     * 
     * 
     * @param sess
     *            the server session
     * @param callback
     *            callback for the retryable operation
     * @return the result of the operation
     * @throws IOException
     */
    public <T> T doInWriteTransaction(SrvSession sess, final CallableIO<T> callback)
            throws IOException
    {
        Boolean wasInRetryingTransaction = m_inRetryingTransaction.get();
        try
        {
            boolean hadTransaction = sess.hasTransaction();
            if (hadTransaction)
            {
                sess.endTransaction();
            }
            m_inRetryingTransaction.set(Boolean.TRUE);
            T result = m_transactionService.getRetryingTransactionHelper().doInTransaction(
                    new RetryingTransactionHelper.RetryingTransactionCallback<T>() {
                        public T execute() throws Throwable
                        {
                            try
                            {
                                return callback.call();
                            }
                            catch (IOException e)
                            {
                                // Ensure original checked IOExceptions get propagated
                                throw new PropagatingException(e);
                            }
                        }
                    });
            if (hadTransaction)
            {
                beginReadTransaction(sess);
            }
            return result;
        }
        catch (PropagatingException e)
        {
            // Unwrap checked exceptions
            throw (IOException) e.getCause();
        }
        finally
        {
            m_inRetryingTransaction.set(wasInRetryingTransaction);
        }
    }

    /**
     * End an active transaction
     * 
     * @param sess
     *            SrvSession
     * @param tx
     *            Object
     */
    public void endTransaction(SrvSession sess, Object tx)
    {

        // Check that the transaction object is valid

        if (tx == null)
            return;

        // Get the filesystem transaction

        FilesysTransaction filesysTx = (FilesysTransaction) tx;

        // Check if there is an active transaction

        if (filesysTx != null && filesysTx.hasTransaction())
        {
            // Get the active transaction

            UserTransaction ftx = filesysTx.getTransaction();

            try
            {
                // Commit or rollback the transaction

                if (ftx.getStatus() == Status.STATUS_MARKED_ROLLBACK ||
                        ftx.getStatus() == Status.STATUS_ROLLEDBACK ||
                        ftx.getStatus() == Status.STATUS_ROLLING_BACK)
                {
                    // Transaction is marked for rollback

                    ftx.rollback();

                    // DEBUG

                    if (logger.isDebugEnabled())
                        logger.debug("End transaction (rollback)");
                }
                else
                {
                    // Commit the transaction

                    ftx.commit();

                    // DEBUG

                    if (logger.isDebugEnabled())
                        logger.debug("End transaction (commit)");
                }
            }
            catch (Exception ex)
            {
                if (logger.isDebugEnabled())
                    logger.debug("Failed to end transaction, " + ex.getMessage());
                // throw new AlfrescoRuntimeException("Failed to end transaction", ex);
            }
            finally
            {
                // Clear the current transaction

                sess.clearTransaction();
            }
        }
    }

    /**
     * Create and start a transaction, if not already active
     * 
     * @param sess
     *            SrvSession
     * @param readOnly
     *            boolean
     * @exception AlfrescoRuntimeException
     */
    private final void beginTransaction(SrvSession sess, boolean readOnly)
            throws AlfrescoRuntimeException
    {
        // Do nothing if we are already in a retrying transaction
        Boolean inRetryingTransaction = m_inRetryingTransaction.get();

        if (inRetryingTransaction != null && inRetryingTransaction)
        {
            return;
        }

        // Initialize the per session thread local that holds the transaction

        sess.initializeTransactionObject();

        // Get the filesystem transaction

        FilesysTransaction filesysTx = (FilesysTransaction) sess.getTransactionObject().get();
        if (filesysTx == null)
        {
            filesysTx = new FilesysTransaction();
            sess.getTransactionObject().set(filesysTx);
        }

        // If there is an active transaction check that it is the required type

        if (filesysTx.hasTransaction())
        {
            // Get the active transaction

            UserTransaction tx = filesysTx.getTransaction();

            // Check if the current transaction is marked for rollback

            try
            {
                if (tx.getStatus() == Status.STATUS_MARKED_ROLLBACK ||
                        tx.getStatus() == Status.STATUS_ROLLEDBACK ||
                        tx.getStatus() == Status.STATUS_ROLLING_BACK)
                {
                    // Rollback the current transaction

                    tx.rollback();
                }
            }
            catch (Exception ex)
            {}

            // Check if the transaction is a write transaction, if write has been requested

            if (readOnly == false && filesysTx.isReadOnly() == true)
            {
                // Commit the read-only transaction

                try
                {
                    tx.commit();
                }
                catch (Exception ex)
                {
                    throw new AlfrescoRuntimeException("Failed to commit read-only transaction, " + ex.getMessage());
                }
                finally
                {
                    // Clear the active transaction

                    filesysTx.clearTransaction();
                }
            }
        }

        // Create the transaction

        if (filesysTx.hasTransaction() == false)
        {
            try
            {
                // Create a new transaction

                UserTransaction userTrans = m_transactionService.getUserTransaction(readOnly);
                userTrans.begin();

                // Store the transaction

                filesysTx.setTransaction(userTrans, readOnly);

                // DEBUG

                if (logger.isDebugEnabled())
                    logger.debug("Created transaction readOnly=" + readOnly);
            }
            catch (Exception ex)
            {
                throw new AlfrescoRuntimeException("Failed to create transaction, " + ex.getMessage());
            }
        }

        // Store the transaction callback

        sess.setTransaction(this);
    }

    /**
     * An extended {@link Callable} that throws {@link IOException}s.
     *
     * @param <V>
     */
    public interface CallableIO<V> extends Callable<V>
    {
        public V call() throws IOException;
    }

    /**
     * A wrapper for checked exceptions to be passed through the retrying transaction handler.
     */
    protected static class PropagatingException extends RuntimeException
    {
        private static final long serialVersionUID = 1L;

        /**
         * @param cause
         *            Throwable
         */
        public PropagatingException(Throwable cause)
        {
            super(cause);
        }
    }
}
